A light field is a mathematical description of intensity, spatial position and direction of light rays in a region. A light field may be parameterized in different ways. For example, the position and direction of a light ray in a 4D light field may be described by 2D spatial coordinates of a point at which the ray intersects a first plane and by 2D spatial coordinates of a second point at which the ray intersects a second, parallel plane. Or, for example, the position and direction of a light ray in a 4D light field may be described by 2D spatial coordinates of a point at which the ray intersects a plane and by two angles (e.g., an azimuthal angle and an altitude angle).
A light field camera can capture light field information about light rays incident on a sensor plane of the camera: e.g., information about the angle and intensity of light rays incident at respective pixels of the sensor plane.
Thus, a light field camera, also called a plenoptic camera, is quite different from a conventional camera. A conventional camera can only measure the amount of light received at respective sensor pixels; it cannot measure the angle at which the illumination strikes the respective pixels. In contrast, a light field camera can measure both the amount and direction of light that strikes respective sensor pixels.